Regarding an intracranial aneurysm, in general, a surgical operation is performed when there is a high risk of a rupture (hereinafter referred to as a “rupture risk”), and follow-up treatment (observation of progress) with medication is performed when the rupture risk is low. At a time of follow-up treatment of an intracranial aneurysm, various methods are used for evaluating the morphology of the aneurysm.
A first method is a method in which an image of the aneurysm is acquired by CTA (computed tomography angiography) or MRI (magnetic resonance imaging), and the shape of the aneurysm is visually evaluated based on this image.
A second method is a method in which, based on the above-described image, the blood flow to the aneurysm is analyzed by a computer, and a shear stress of the inner wall (WSS: wall shear stress) is evaluated.
It has begun to be understood by studies in recent years that an intracranial aneurysm occurs due to an excessive pressure (stress) on the inner wall by the blood flow, and the inner wall becomes fragile due to a decrease in stress, resulting in a rupture.
Thus, according to the inventor's study, when the rupture risk of the aneurysm is to be analyzed (derived), it is useful to analyze such shape, size and distortion of an aneurysm as to decrease the stress on the inner wall.
However, a method of analyzing such shape, size and distortion of an aneurysm has not yet been proposed.
The purpose is to provide a system and a derivation method, which can analyze such shape, size and distortion of an aneurysm as to decrease the stress on the inner wall.